Internal Bathroom - issues with ventilation

I'm thinking of changing my internal main bathroom (no windows) from bath / over bath shower to no bath and an electric shower. May go the wet room route but not sure just yet.

I know I will need to sort some kind of ventilation, but don't have a clue about what would be needed. The room is in the middle of the house - maybe 15 foot from an outside wall. It's a bungalow so directly above it is the attic. What would be my options?

Would like to get an idea of what could / should be done before I start speaking to plumbers (as I don't have much knowledge in this)

Thanks